“I know one of the reasons,” said Vince Marsaglia, vice president of Pizza Port. “I don't tell the brewers how to brew.”

Luck plays a role, too, Marsaglia insisted. In some categories, more than 100 beers are entered. Last weekend, 132 judges from 10 nations worked diligently — oh, those long hours bent over a beer mug! — to find the best of the best. But the difference between champion and better-luck-next-time can be slight.

“It's a crapshoot,” Marsaglia said. “It's so often a matter of interpretation.”

While trying to maintain consistency in his beers, Bagby keeps an eye on new trends. Last weekend in Denver, he spotted plenty of “session” ales, beers with a modest alcohol content of 3 percent to 4 percent; Belgian-inspired beers; barrel-aged brews; and some smashing ale-lager hybrids.

“Everyone's continuing to be creative,” he said. “More and more different beers are coming out, but at the same time you see a lot of the classic styles.”

Over the years, the Great American Beer Festival has changed to keep pace with beer fans and brewers. In 1983, all festivalgoers could vote on any and all beers; the most popular three were given “consumer choice” awards. Since the late 1980s, though, entries have been scored by trained judges who can distinguish between a Bohemian-style pilsner, for instance, and a German-style pilsner.

With dozens of categories, hundreds of breweries and thousands of entries, what does it take to win?

“You look at the numbers and see that San Diego County — and northern San Diego County especially — seems to pull down a fair number of medals,” Bagby said.